With the popularization of broadband access and the rapid development of streaming media-based broadband applications, Content Delivery network (CDN) is found an effective means of effectively mitigating the pressure exerted on a backbone network by high throughput of streaming media transmission and improving the quality of service of the streaming media. Therefore, in recent years, the CDN has attracted more and more attention and have been deployed widely at home and abroad, and streaming media content has also replaced Web content as the main object borne by the CDN.
The core idea of the CDN is to replicate data content from the center network to an edge close to users. In this manner, the performance for the users to access content is effectively improved, and the pressure on center equipment and the bone network is effectively reduced, and through the CDN, content is changed from the original centralized structure to a distributed structure.
A single CDN server is equivalent to a cache node and can only provide limited cache and service capabilities. Therefore, it is required to establish a cache node group which is formed by multiple CDN servers and performs collaborative works in collaborative caching mode, where cache space of the CDNs are fully used to improve the hit ratio, disperse hotspot data, and balance loads of the servers, thereby preventing failure of a single point, and solving the bottleneck problem.
The single internal storage space of a CDN cache node according to the prior art is used for storing both local data content for local access and collaborative data content for non-local access. Meanwhile, in the collaboration, because only the global collaboration objective is taken into consideration, the CDN cache nodes participating in the collaboration are completely equivalent, but no attention is placed on different demands for the local optimization of caching.